[John Milner]

I bought a 69 GTO dash wiring harness and an engine harness that is made with an hei style wire. The dash harness has a wire from the ignition switch plug to the bulk head that is marked “resistance”. This resistance wire will plug into the hei wire on the engine harness when the engine harness is plugged into the dash harness bulkhead. Please correct me if I’m wrong, but won’t the hei run wire not have a full 12 volts if it plugs into the wire marked “resistance”?

Thanks

[johnta1]

If it is a resistance wire it will not be a full 12 volt. You can measure it with ohm meter to see what it reads?

[John Milner]

Thanks. The dash is currently out of the car to be installed soon. My engine harness I have has the thicker red wire and connector that plugs into this resistor wire that runs under the dash. I had thought about just removing the HEI plug in from the new engine harness and install an end that will go to my coil stud and just use the thicker wire. I also have a points style wire from another 69 harness that I could remove from the plug and install on the new harness in place of the red HEI wire if it was needed. Once I get the dash in and engine harness in I will check voltage. It is just easier to modify things while they are out if any modifications are needed.

[brad01]

Once my car fires cold its 12.2 volts and as it warms up a couple minutes it will drop to 9.7 factory resistor wire

[gtobird]

Originally Posted by brad01

Once my car fires cold its 12.2 volts and as it warms up a couple minutes it will drop to 9.7 factory resistor wire

Just to clarify.........

I believe the factory wiring for a points type distributor was set up so that when you turn the key to the start position with the starter turning, the voltage to the distributor is fed off the start circuit directly at the full 12 volts. When you let go of the key, and the key is in the "run" position, the starter circuit is then open and voltage is fed off of the "run" position circuit through the resistance wire so it then drops to something less than 12 volts (9.7 volts may very well be correct). My understanding is that a full 12 volts to the points will fry up the points quickly if left running so the auto manufacturers wanted to keep full voltage at the distributor when cranking for a hot spark and then drop it back down right after the engine was running.

In a factory wiring setup for our cars built with points distributors, it's not a matter of whether your car is hot or cold. It just has to do with the position your key is in as to how many volts are fed to the distributor. Admittedly, you could possibly have a modified setup with a temperature sensor (switch) with a resistance circuit to drop the voltage when the engine is warm. I've never seen that done, but there are all sorts of ways to do this stuff if you are electrically inclined.